643 
Microscopical examination . — Besides the fat globules, the micro- 
scope may reveal the presence of colostrum corpuscles, blood, pus, 
epithelial cells, bacteria, and granular detritus. The presence of colos- 
trum corpuscles is abnormal after the twelfth day of lactation. Blood 
and pus are always abnormal. The presence of blood and pus in the 
milk require the suspension of lactation until they disappear. 
Determination of fat . — The simplest method of determining the fat 
of woman's milk is by Holt’s cream gauge. This is a graduated tube 
on a foot, with a glass stopper. The tube is filled with freshly drawn 
milk to the zero mark at the top of the scale and the whole allowed 
to stand at room temperature for twenty-four hours. The percentage 
of cream according to the scale is then read off. The ratio of the 
cream to the fat content is as 5 : 3, e. g., 5 per cent of cream equals 3 
per cent of fat, etc. 
While not very accurate, this method suffices for clinical purposes. 
Results approximating the accuracy of a chemical analysis may be 
obtained by the Babcock test or by Lewis’s modification of the Leffman 
and Beam test for cow's milk (Holt). This is a centrifugal test for 
which special tubes are required, which, however, may be used in the 
ordinary centrifuge for urine. ' 
Sugar . — The percentage of sugar in human milk. is subject to very 
little variation, and may be regarded as constant for clinical purposes. 
Proteids . — The determination of the proteids in woman’s milk is an 
elaborate process requiring the resources of a well-equipped chemical 
laboratory. 
We may, however (according to Holt), gain an approximate idea 
of their percentage by considering the sugar and salts of milk as con- 
stants not affecting its specific gravity and estimating the proteids 
from our knowledge of the fat content of the specimen. Xow, the 
specific gravity will vary directly with the proteids and inversely to 
the fat, viz, high proteids, high specific gravity; high fat, low spe- 
cific gravity. The following table shows the application of this 
principle : 
Variations in the composition of womans milk as deduced by observation of 
the specific gravity and the fat content (Holt). 
Specific gravity, 70° F. 
Cream, 24 hours. 
Proteids, estimated. 
\verage 
1,031 
7 per cent 
1.50 per cent. 
Normal (rich milk). 
Normal (fair milk). 
formal variations 
1 028-1,032 
8-12 per cent 
Normal variations 
1,031 
5-6 per cent 
Abnormal variations 
Low (below 1,028) 
High (above 10 per cent) . 
Normal or slightly 
Abnormal variations 
Low (below 1,028) 
Low (below 5 per cent) . . . 
below. 
Low (very poor milk) . 
\ hnormal variations 
High (above 1,032) . . . 
High 
Very high (very rich 
Abnormal variations 
High (above 1,032) . . . 
Low 
milk). 
Normal or nearly so. 
